/*
 * Copyright (c) 2005, 2006, Oracle and/or its affiliates. All rights reserved.
 * ORACLE PROPRIETARY/CONFIDENTIAL. Use is subject to license terms.
 *
 *
 *
 *
 *
 *
 *
 *
 *
 *
 *
 *
 *
 *
 *
 *
 *
 *
 *
 *
 */
package javax.swing.plaf.nimbus;

import java.awt.image.BufferedImage;
import java.awt.image.Raster;
import java.awt.image.WritableRaster;
import java.util.Arrays;

/**
 * DropShadowEffect - This effect currently only works with ARGB type buffered
 * images.
 *
 * @author Created by Jasper Potts (Jun 18, 2007)
 */
class DropShadowEffect extends ShadowEffect {

  // =================================================================================================================
  // Effect Methods

  /**
   * Get the type of this effect, one of UNDER,BLENDED,OVER. UNDER means the result of apply effect
   * should be painted under the src image. BLENDED means the result of apply sffect contains a
   * modified src image so just it should be painted. OVER means the result of apply effect should
   * be painted over the src image.
   *
   * @return The effect type
   */
  @Override
  EffectType getEffectType() {
    return EffectType.UNDER;
  }

  /**
   * Apply the effect to the src image generating the result . The result image may or may not
   * contain the source image depending on what the effect type is.
   *
   * @param src The source image for applying the effect to
   * @param dst The destination image to paint effect result into. If this is null then a new image
   * will be created
   * @param w The width of the src image to apply effect to, this allow the src and dst buffers to
   * be bigger than the area the need effect applied to it
   * @param h The height of the src image to apply effect to, this allow the src and dst buffers to
   * be bigger than the area the need effect applied to it
   * @return Image with the result of the effect
   */
  @Override
  BufferedImage applyEffect(BufferedImage src, BufferedImage dst, int w, int h) {
    if (src == null || src.getType() != BufferedImage.TYPE_INT_ARGB) {
      throw new IllegalArgumentException("Effect only works with " +
          "source images of type BufferedImage.TYPE_INT_ARGB.");
    }
    if (dst != null && dst.getType() != BufferedImage.TYPE_INT_ARGB) {
      throw new IllegalArgumentException("Effect only works with " +
          "destination images of type BufferedImage.TYPE_INT_ARGB.");
    }
    // calculate offset
    double trangleAngle = Math.toRadians(angle - 90);
    int offsetX = (int) (Math.sin(trangleAngle) * distance);
    int offsetY = (int) (Math.cos(trangleAngle) * distance);
    // clac expanded size
    int tmpOffX = offsetX + size;
    int tmpOffY = offsetX + size;
    int tmpW = w + offsetX + size + size;
    int tmpH = h + offsetX + size;
    // create tmp buffers
    int[] lineBuf = getArrayCache().getTmpIntArray(w);
    byte[] tmpBuf1 = getArrayCache().getTmpByteArray1(tmpW * tmpH);
    Arrays.fill(tmpBuf1, (byte) 0x00);
    byte[] tmpBuf2 = getArrayCache().getTmpByteArray2(tmpW * tmpH);
    // extract src image alpha channel and inverse and offset
    Raster srcRaster = src.getRaster();
    for (int y = 0; y < h; y++) {
      int dy = (y + tmpOffY);
      int offset = dy * tmpW;
      srcRaster.getDataElements(0, y, w, 1, lineBuf);
      for (int x = 0; x < w; x++) {
        int dx = x + tmpOffX;
        tmpBuf1[offset + dx] = (byte) ((lineBuf[x] & 0xFF000000) >>> 24);
      }
    }
    // blur
    float[] kernel = EffectUtils.createGaussianKernel(size);
    EffectUtils.blur(tmpBuf1, tmpBuf2, tmpW, tmpH, kernel, size); // horizontal pass
    EffectUtils.blur(tmpBuf2, tmpBuf1, tmpH, tmpW, kernel, size);// vertical pass
    //rescale
    float spread = Math.min(1 / (1 - (0.01f * this.spread)), 255);
    for (int i = 0; i < tmpBuf1.length; i++) {
      int val = (int) (((int) tmpBuf1[i] & 0xFF) * spread);
      tmpBuf1[i] = (val > 255) ? (byte) 0xFF : (byte) val;
    }
    // create color image with shadow color and greyscale image as alpha
    if (dst == null) {
      dst = new BufferedImage(w, h,
          BufferedImage.TYPE_INT_ARGB);
    }
    WritableRaster shadowRaster = dst.getRaster();
    int red = color.getRed(), green = color.getGreen(), blue = color.getBlue();
    for (int y = 0; y < h; y++) {
      int srcY = y + tmpOffY;
      int shadowOffset = (srcY - offsetY) * tmpW;
      for (int x = 0; x < w; x++) {
        int srcX = x + tmpOffX;
        lineBuf[x] = tmpBuf1[shadowOffset + (srcX - offsetX)] << 24 | red << 16 | green << 8 | blue;
      }
      shadowRaster.setDataElements(0, y, w, 1, lineBuf);
    }
    return dst;
  }
}
